Electronically controlled hot water recirculation pump

ABSTRACT

A water pump controlled by a microcontroller and operated to pump hot water for specific recirculation periods during a multi-day cycle. The recirculation periods are determined from hot water usage data logged by the microcontroller during a logging period occurring in the previous multi-day cycle. A preferred cycle is during a seven-day, or one-week, period.

This application claims the benefit or priority pursuant to 35 U.S.C.119(e) from U.S. Provisional patent application having application No.61/305,805 filed Feb. 18, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a processor controlled water pump.

2. Description of the Related Art

In some parts of the country, hot water is often continuously circulatedwithin the closed water system of a house or business. This is done toreduce the wasting of flowing water while waiting for the hot water toreach a tap in a bathroom or kitchen of a house or office center; theidea is if the water is kept hot at all times, a user will get hot waterinstantaneously when the user has a demand for hot water. Presumably,the circulating of hot water continuously makes it available at varioustap points in a system as needed, thus eliminating the need to run thewater at the tap point until it reaches a desired temperature before itcan be used.

One example, is a user wanting to take a shower on a cold morning;without the continuously circulating hot water, the user will turn onthe shower, and as the piping system will generally have cooled down tono higher than room temperature by the morning, all of the water in thepipes must be exhausted through the tap, before the hot water stored inthe hot water tank reaches the shower head. The user must wait until thewater reaches a “comfortable” temperature while the shower is running.This wastes valuable water because the user waits for the water to reacha comfortable temperature while the tap is running before he/she canstart to use the water. The continuous pumping of the hot water tocirculate it throughout a water system thus eliminates the inherentwaste of water in non-circulating systems. However, relatively largeamounts of energy are needed to circulate the water continuously andthus this approach is wasteful, because heat loss occurs in the pipingand most practical real world systems have large periods of time whereno one is using the hot water and yet it is still being circulated andmaintained at a relatively high temperature.

In some areas, instead of continuously circulating the water in thesystem, a pump can be made to operate in a continuous pulse mode, i.e.,on for a period and off for a period, on a continuing basis. Forexample, a pulse mode can comprise 75 seconds on and 15 minutes off, allday, every day.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a smart pump which is controlled by amicrocontroller, and method for instructing the microcontroller bycontinuously receiving data from the hot water system circulated by thesmart pump. The circulation of hot water is done at various times calledrecirculation periods which are time periods during which hot waterusage is expected based on logged hot water usage data, from a priorbase period. That is, the microcontroller logs occurrences of hot waterusage during a data logging period and then operates a water pump inaccordance with this hot water usage data pattern, during theimmediately subsequent period. The smart pump comprises a water pumpmechanism coupled to and controlled by a microcontroller which logs hotwater usages based on signals received from one or more sensors thatdetect occurrences of hot water usage by detecting a temperatureincrease in the hot water system. With the use of a sensor, a minimumthreshold can be set for a temperature increase. When the temperatureincrease equals or surpasses the threshold, such an increase is detectedby the sensor which sends a signal to the microcontroller indicating theincrease. Upon receipt of the signal from the sensor, themicrocontroller togs and records the hot water usage, at that particulartime. The sensors as well as the microcontroller and related circuitrymay be located within the water pump mechanism. The sensors may also belocated external to the water pump mechanism. Depending on the state ofa user operated automatic switch coupled to the microcontroller, thesmart pump can operate in a continual pulse mode or an automatic mode,or be turned off completely.

In the pulse mode, the smart pump functions by pumping hot watercontinuously for a defined period of time every cycle. The cycles arecontiguous time periods. In the automatic mode, the microcontrollercontrols the water pump mechanism to operate in accordance with theprevious data logging period's hot water usage. The data logging periodcomprises one or more recirculation periods during a day, each of whichis a period encompassed by a start usage cycle and an end usage cycle.

The recirculation period may comprise one or more start/end usage cyclesand the data logging period comprises one or more recirculation periods.While logging data, the microcontroller can continue to operate the pumpin accordance with a current usage pattern. The current data usagepattern may define the start and end of the recirculation periods beinglogged. Once the data logging period expires, the microcontroller, whenin automatic mode, operates the water pump mechanism in accordance withthe logged usage data pattern. The microcontroller may start anotherdata logging period and proceed to start logging usages of hot wateronce again over a data togging period of the same length or of adifferent length to generate another hot water usage data pattern andagain update the operation of the water pump mechanism when this nextdata logging period expires. It should be noted that during arecirculation period, a pump may operate continuously or in a pulsemode; the pulse mode, for example, providing for the pump being on for75 seconds, off for 15 minutes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of a preferred smart pump installed in a hot watersystem of a newly constructed household.

FIG. 1B is a diagram showing a possible location of a preferred smartpump installed a retrofitted hot water system of a household.

FIG. 2 is a flow chart representing the operation of the smart pump inautomatic mode and pulse mode.

DETAILED DESCRIPTION

Referring to FIG. 1A, there is shown the smart pump of the presentinvention which comprises an electrically controlled water pumpmechanism 130 coupled via a digital bus or signal interface 120 to amicrocontroller 122 having an N-input port 124 for receiving signalsfrom one or more sensors 150, 151, . . . 160 located within the pumpingmechanism 130 or remotely from the water pumping mechanism 130 and oneof said input ports, 150, is used to receive the state of a usercontrolled AUTO switch (not shown) for setting the smart pump of thepresent invention in automatic mode as described below. N is an integerequal to 1 or greater. For ease of explanation and to provide somecontext to the operation of the smart pump of the present invention, itis shown as part of a closed water system of a household. The system hasa hot water tank 102 which receives cold water via pipe segment 118 andgenerates hot water provided to water pumping mechanism 130 via pipesegment 104. Water pump mechanism 130 pumps the hot water via pipesegment 106 to various hot water taps 108, 110, 112, and 114. The hotwater return path is provided by pipe segment 132.

When set to the automatic mode with the AUTO switch (not shown), waterpump mechanism 130 pumps the hot water in accordance with the method ofthe present invention as described herein. The various hot water tapsare typical locations (e.g., kitchen, bathroom sink, tub/shower,laundry) in a household where hot water is used for various purposes.The smart pump is powered with power cord 128 connected to AC outlet 134for providing power. In other embodiments, the smart pump may be poweredby batteries disposed within a cavity of the water pumping mechanism.Also, microcontroller 122 along with signal interface 120, input port124 and associated circuitry may be disposed within the same or othercavity of water pumping mechanism 130. For ease of explanation, however,microcontroller 122, signal interface 120 and input port 124 are shownas being external to the water pumping mechanism 130. Microcontroller122 may be any relatively inexpensive microprocessor or microcomputerintegrated circuits that can be programmed with commands using manycommercially available software packages. The programming language canbe any well known High Level programming language.

The smart pump of the present invention can further comprise at leastone sensor that detects the opening of a hot water tap, by changes inthe flow of water in the hot water line, or by changes in thetemperature of the water or pipe during a period when the pump is not inoperation. To prevent accidental operation of the smart water pump, themicrocontroller optionally can be programmed to require that the flow ofwater continue for a defined minimum period of time, before it islogged. The length of such period depends on the particular sensor beingused and/or on the requirements of the closed water system.

The sensor can be located within a cavity of the water pump mechanism130, especially at the inlet to or outlet from the pump. Optionally, asensor can be remotely located from the water pump mechanism 130, e.g.,in FIG. 1B, hereto, the sensor is located at the desired location 106,and the pump located elsewhere, e.g., in pipe 132 at location 126,in-line with pipe 132, downstream from the taps, as shown in FIG. 1B, insimilar fashion as it is installed in line with pipes 104 and 106, asshown in FIG. 1A. This often is the case when the system of thisinvention is installed after construction of the building, because itmay not be convenient or efficient to install the pump upstream from thetaps. A sensor at location 106, in the system of FIG. 1B, is remotelylocated from the pump 130, but is within the supply flow pipe segment104/106, for detecting the flow of hot water resulting from hot waterusage at any of the taps 108-114. When the pump is part of the originalsystem included with the original construction of the building, thesensor is preferably located within the pump, at location 106, upstreamof the taps. Either a remote sensor or a sensor disposed within thewater pump mechanism (but not both) can be used.

As a further alternative, a sensor can be disposed at one or more of thetaps (110, 112, 114), to give a direct indication of flow through thattap.

It will be readily understood by one skilled in the art to which thisinvention belongs that water pump mechanism 130 can be any type ofelectrically controllable or electronically controllable mechanismdesigned to operate when triggered by one or more electronic orelectrical signals. As shown here, the control signals for operating thewater pump mechanism 130 are transmitted from the microcontroller 122over electrical control motor interface 120. If desired, a wirelessconnection can also be provided.

The water pump mechanism 130 may require electric signals of a certainvoltage and current for proper operation. The control signals aretransferred via the control motor interface 120 to operate, e.g., anon/off switch for the water pump mechanism130; such control signals canbe transformed or converted to electrical signals of the proper voltageand/or current sufficient to operate the pumping mechanism 130. Theparticular location of the sensor(s) may sometimes reflect the time ofinstallation of the smart pump of the present invention. Generally,smart pumps installed during construction of a structure (private houseor commercial structure) are located intermediate the hot water source(in FIG. 1A, a hot water tank 102 and the hot water taps, e.g., tap 108)and have sensor(s) located within or immediately adjacent the water pumpmechanism 130; and a smart pump installed after construction can belocated at another more accessible part of the hot water system, forexample in the “Hot Water Return” line, as shown in FIG. 1B; and in thatcase the sensor is located remotely from the water pump mechanism 130,such as, preferably, at location 126 within the supply flow pipe line104, downstream from the hot water tank.

When a sensor detects hot water flow or a sufficient temperature change(e.g., a temperature rise) it sends a signal via a wire (or wirelessly)to the microcontroller 122. Additional circuitry (not shown, butconventionally available) is typically needed to convert the sensorsignal to a proper format for reception by the microcontroller 122. Uponreception of the sensor signal, it is logged by the microcontroller 122,which controls the water pumping mechanism 130 and causes it to performthe steps of the method of the present invention.

Referring now to FIG. 2 there is shown a flow chart of the method of thepresent invention. Initially, power is provided to the smart pump andmicrocontroller of the present invention in step 202. In step 204,microcontroller 122 reads the status of its input port corresponding tothe AUTO switch to determine whether a user of the smart pump hasswitched the smart pump to automatic operation. If automatic operationis not selected, the method of the present invention moves to step 230and enters the, e.g., PULSE mode wherein the smart pump continuouslypumps water (regardless of the sensor output) for a period of e.g., 75seconds every 15 minutes, or it can be in the Off mode, where the pumpis not operating. As FIG. 2 shows, the smart pump of the presentinvention wilt remain in an operating mode, e.g., the PULSE mode ofoperation, or Off, until the AUTO switch is set to the automatic mode.

The method of the present invention moves to step 206 whenmicrocontroller 122 has detected that AUTOMATIC operation has beenselected. In step 206, microcontroller 122 initializes a counter (i.e.,a timer) that is to indicate the logging period during which varioususages of hot water are detected, the length of time of each of saidusages, the beginning and end of each of said usages. Documenting thetime at which the initial daily hot water usage is detected, the lengthof each said usages and the beginning and end of each said usage, foreach day, constitute logging a water usage. These various usages arelogged within a certain time period and thus this period (typically 7days) is referred to as the data logging period. Also, in step 206another timer can be provided (called the no usage counter) which can beset to measure any period of no hot water usage that exceeds a certainthreshold. For example, the threshold may be set to 36 hours. If no hotwater usage is detected for 36 consecutive hours, the method of thepresent invention will cause the smart pump to enter into an IDLE orOff, mode of operation during which the smart pump does not pump anywater until it detects hot water usage or detects a signal to restart.Thus, for example, after step 206, the method of the present inventionmoves to step 208 wherein microcontroller 122 monitors the sensor(s). Ifhot water usage is not detected, the no usage timer continues to measurethe time of no usage and when that time exceeds a predefined period (36hours, in our example) the smart pump enters the IDLE mode but themicrocontroller continues to monitor the sensor(s). This is reflected bysteps 208 to 210 to 226 to 224 and then back to step 208. The method ofthe present invention will remain in this IDLE loop defined by theaforementioned steps until it detects hot water usage or is signaled torestart. Note that during the IDLE mode of operation, the timermeasuring the data togging period is also running. This will allow thepump to remain idle if there are days during the data logging period(e.g., 7-day period) when there is no hot water flow. Examples of no hotwater usage include time periods when no one is occupying a residencedue to vacation or occupants are away for a weekend for example.

The method of the present invention then moves to step 212 wheredetection of hot water usage by a sensor has occurred and the resultingsensor signal is read by microcontroller 122. In step 212 the method ofthe present invention resets the no usage counter to zero time.Effectively, each time hot water usage is detected, the no usage counteris reset to zero. In step 214, start and end usage cycles (e.g., thedaily start times and end times of hot water usage) of the detectedwater usage are detected, for each day, but a pre-run period of Xminutes and a post-run period of Y minutes is recorded or logged for thestart usage cycles and end usage cycles respectively. For example, if ona Tuesday, hot water usage is detected at 8:10 am at a fixture, then thefollowing Tuesday, hot water will be supplied to that fixture startingat 7:10 am and ending at 9:10 am; here X, the pre-run period is 60minutes and Y, the post run period is also 60 minutes.

In another example, if a shower was used on a Friday starting at 6:00 amand ending at 6:15 am, then the following Friday, hot water will bepumped to that shower starting at 5:00 am until 7:15 am where once againX and Y are 60 minutes. It will be readily obvious that the length ofthe X and Y periods is arbitrary and different X and Y times can beprogrammed. Also in the circumstance where there are different sensorsat different taps or fixtures throughout the house or structure, the Xand Y times can be programmed for a sensor located at each such tap orfixture. Also, the X and Y times need not necessarily be equal to eachother. X and Y are variables representing time periods in minutes, hoursor seconds or any combination thereof.

Throughout the data togging period, the method of the present inventiondetermines e.g., daily start cycles and end cycles as follows. The startof a usage cycle is determined by a sudden increase in the flow of waterthrough the hot water line, as occurs when a tap is opened.Alternatively, the start of a usage cycle is determined by a time rateof change of water temperature of K degrees per L minutes after the pumphas been off for M minutes or when the pump has been off for P minutesand the water temperature remains “hot.” A “hot” water temperature isdefined by a particular temperature deemed to be “hot” by the sensor(s)communicating with the microcontroller 122. That is, the sensor(s) canbe set at a particular threshold temperature which if surpassed by theflowing water will cause the sensor(s) to indicate detection of “hot”water. An end usage cycle is defined as a no usage period of Z hours ofno usage; for example Z can equal to 2.8 hours. The variables K, L, M, Pand Z represent real numbers greater than zero.

A start usage cycle can represent the start time of a recirculationperiod. An end usage cycle can represent the end time of a recirculationperiod. That is, a recirculation period is defined by the periodencompassed by a stored start usage cycle time and a stored end usagecycle time. A recirculation period may, therefore, comprise one or morestart/end usage cycles, in steps 216 and 218, the start and end of therecirculation periods are thus determined from data gathered by thesmart pump from the prior data togging period. At the end of the firsttogging period, the pump will operate during a second logging period inaccordance with the data logged and accumulated during the first loggingperiod. During the second and subsequent logging periods, while the pumpis operating in accordance with the usage cycles defined from theprevious data logging period, the sensors and microcontroller continueto operate in accordance with the method of the present invention andcontinue to measure, log and record the times of hot water usage anduses the new data to determine the times of operation of the pump forthe succeeding data logging period; the recirculation periods are thuscontinually updated. The method of the present invention continues tolog data for the duration of the logging period (e.g., 7 days). Once thedata togging period expires at step 228, the hot water usage datapattern that has been logged by the controller is used to update theoperation of the smart pump in step 222. In step 220, the pump isoperated in accordance with the updated hot water usage data pattern forat least another data togging period and the method of the presentinvention continues to monitor and log(or record) new data usage timeswhite the smart pump is operated as per the last updated data pattern.

In one embodiment of the present invention, the data measured determinesthe earliest and latest times that hot water is used during any day ofthe logging period, and sets those times as the beginning and end of thepump operation during every day of the succeeding logging period.However, another embodiment can be used to tog the usage times for eachday of the week, and change the usage times accordingly. For example,during Monday to Friday of the week, the usage times start and endearlier each day. On the weekends, the usage times can start and endlater each day.

The smart pump can be configured with a built-in power source and duringa power outage, the smart pump may not be able to pump water, but whenpower is restored, the smart pump can return to its operating modestatus immediately prior to the power outage. Another embodiment allowsthe smart pump to start a new data logging period upon restoration ofpower, the previous data having been lost when power is lost. Similarly,the microcontroller may have an initial setting pre-programmed in itssystem that will operate the pump during the initial start-up toggingperiod, based upon the common usage of the general population, or it maybe programmed when purchased to meet the requirements of the individualpurchaser.

The device and method of the present invention have been described interms of various embodiments as described herein. It will be readilyunderstood that the embodiments disclosed herein do not at all limit thescope of the present invention. One of ordinary skill in the art towhich this invention belongs can, after reading the disclosure,implement the device and method of the present invention using otherembodiments that are different from those disclosed herein but which arewell within the scope of the invention as claimed below.

What is claimed is:
 1. A method for controlling the flow of hot water ina building hot water system, the hot water system comprising a source ofhot water, a piping system for containing a flow of hot water, a waterpump mechanism operatively connected to the piping system for causingthe flow of hot water from the source through the piping system, asensor for sensing the flow of hot water through the hot water system, amicrocontroller operatively connected to the sensor to receive a signalindicating the flow of hot water, the microcontroller also being capableof logging and recording the signal during a pre-defined data loggingperiod, and for controlling the pump to cause hot water flow during asubsequent data logging period;, the method comprising: during apre-defined data logging period, logging and recording on themicrocontroller, signals from the sensor indicating the times for theperiods of a flow of hot water through the hot water system during eachday of the data logging period to obtain usage patterns data during thedata logging period; and during a succeeding pre-defined data periodcontrolling the operation of the water pump mechanism with themicrocontroller to operate the water pump mechanism to maintain a flowof hot water in accordance with the logged usage pattern data obtainedduring the previous defined data logging period; and during thesucceeding pre-defined data period, logging and recording on themicrocontroller, signals from the sensor indicating the times for theperiods of a flow of hot water through the hot water system during eachday of the succeeding data period to obtain usage patterns data duringthe succeeding data logging period updating the logged usage patterndata obtained during the previous defined data logging period,representing the water usage patterns upon expiration of the succeedingpre-defined data logging period; and operating the water pump mechanismduring a second succeeding data period, in accordance with the updateddata.